Firstly I hope that this is the right place to post these questions. Secondly apologies for what I feel will be a lengthy post.

I bought a cheap TPA3116D2 50W*2+100W 2.1amp with the idea to use it in my car. I am powering it with a 5v 2.4a power bank. It's only a little classic car that has no sound system at all. I realise I'm not going to get much power with this setup, but I'm just looking for somethings that I can integrate into the car and sounds a little better than my current little bluetooth speaker.I'm not looking to spend vast amounts of money on this

I tried out the system hooked up to my friends little 25w 6ohm speaker and it worked great for what I want. My question is what speakers and subwoofer should i get? or do I even need a subwoofer with such little power?
tl;dr: Basically I'm confused and looking for recommendations for some simple low cost 2.1 speaker setup that's low cost and sounds ok.

I have a few options:

- Buy some 2.1 computer speakers and convert them to use with my amp. I have found a few ones for around £50 that have ~80w rms. which I think is fine for my needs.

And this is where I get confused: My other option is buy some car speakers or some diy hifi speakers and build a little enclosure for them. That way I can spec them for my car.

I found these little drok 15w speakers. Which I was planning to match with this sub.

Then I found some car speakers such as these and it got me wondering do I need a dedicated subwoofer if the sub starts at 65hz and these start at 40hz?

Basically I'm confused and looking for recommendations for some simple low cost speakers.